Fearfully useful: Scientists reveal how fear improves health

Researchers from Aarhus University, Denmark, have found that experiencing fear for recreational purposes, such as visiting a haunted house or scare room, can reduce inflammation levels in people with low-level chronic inflammation.

Fear and acute stress responses are fundamental survival mechanisms, activating the adrenergic system and triggering "hit or run" reactions. Although chronic stress is associated with harmful low-level inflammation, short-term activation of this system may have a positive effect on the immune system. A team of scientists became interested in how voluntarily experiencing fear could affect inflammation levels in humans.

In their study, titled "Unravelling the effects of entertaining fear on inflammation: a prospective cohort field study," published in the journal Brain, Behavior, and Immunity, the scientists recruited 113 adult visitors to a high-intensity haunted house in Vaile, Denmark.

The participants, whose average age was 29.7 years (69 women and 44 men), had their heart rates monitored throughout the event, which lasted an average of nearly 51 minutes. They self-rated their level of fear using a Likert scale ranging from 1 to 9.

Blood samples were taken immediately before, immediately after, and three days after the visit to measure high-sensitivity C-reactive protein (hs-CRP) levels and immune cell counts. Low-level inflammation was defined as hs-CRP levels above 3 mg/L.

Of the 22 participants with low-level inflammation before the event, 18 (82%) had a decrease in hs-CRP levels three days after the haunted house visit: mean levels decreased from 5.7 mg/L to 3.7 mg/L. Total leukocyte and lymphocyte counts decreased in the entire group when comparing values before and three days after the event, although mean levels remained normal.

The decrease in inflammatory markers in those who initially had increased inflammation suggests that experiencing fear in entertainment may reduce immune responses. These findings are consistent with animal studies showing that acute stress can mobilise inflammatory cells and prepare the immune system for possible injury or infection.

People often seek out thrills that induce fear, from ghost stories and pranks to modern horror films and visits to haunted houses. This experiment shows that such experiences can not only provide adrenaline, but also potentially have health benefits by modulating immune responses.

However, further research is needed to confirm these effects and explore the mechanisms underlying the link between entertaining fear and immune function before such techniques can be considered for medical applications.

Study details: Marie Louise Bønnelykke-Behrndtz et al, Unraveling the effect of recreational fear on inflammation: A prospective cohort field study, Brain, Behaviour, and Immunity (2024). DOI: 10.1016/j.bbi.2024.10.036